Quoted from PinMonk:Rick and Morty seems to be worse than the other spooky ones tested so far (on the right flipper, mainly as it gets a workout). Although of all the machines tested so far, Stranger Things is the champ with temps that maxed out my gauge at over 157 degrees (so I don't know how high STh goes).
But in general, with coils you're fighting the laws of thermodynamics. Energy is converted to action and heat, and if there's not enough time between pulses to let the heat dissipate, the heat continues building, which increases resistance, which increases heat, in a loop. Unlike the other coils in the game, the flippers are firing all the time with few pauses of more than a few seconds, so they just build up heat, which affects their performance over time. Some games are better at building pauses into the action that gives the coils time to cool for short bursts. The fans just help continuously dissipate the heat to prevent heat buildup and in turn electrical resistance. All of that said, if your playing time is 30 minutes or less, you don't have to worry about fade. It only happens over time, but once it starts, it only gets worse unless you let the machine rest (and the heat of the coils dissipate).
Here's a really easy explanation of electrical resistance:
https://nationalmaglab.org/education/magnet-academy/watch-play/interactive/heat-resistance
Thank you for the detailed explanation.